Heart rate and oxygen consumption of helicopter and Irons. port aircraft pilots were measured. During flight operations, the heart rate accelerated without a corresponding increase in oxygen consumption. This heart rate increase beyond that expected from the oxygen uptake, i.e. additional heart rate, is therefore used as an indicator of psychoIogical activation. This activation did not depend only on the actual task, but also on the experience level of the pilot himself. The levels of heart rate (and blood pressure) recorded indicate that even routine missions may impose a hazard to pilots with unmanifested or latent heart failure. This obviously calls for frequent workload-ECG examinations of flying personnel.Abstract
The effect of combined cold (5°C air) and hypoxia (14% oxygen in nitrogen) on water exchange was studied using 24 male rats divided into four equal groups. During a 5-d control period, distilled water and food intakes, urine output and body weight were measured daily. A t the end of this time, Group 1 served as control while Group 2 was exposed to 14% oxygen; Group 3 to air at 5°C and Group 4 to both. All measurements continued during a 30-d experimental period. Regression analysis of water intake on urine output revealed that at a given water intake, all three treated groups excreted significantly more urine than controls. N o significant differences occurred among treated groups. Dehydration (24 h) was carried out on the 28th day of the experiment to assess renal concentrating ability. Both the cold-and cold-hypoxia-treated groups failed to reduce urine volume to that of controls. These same groups also showed little change in urine output in response to subcutaneous administration of 300 m U of Pitressin tannate in oil whereas both the control and hypoxia-treated groups showed a significant decrease. Water intakes of all treated groups during the first hour after return to control environment (26°C, 20.9% oxygen) were significantly greater than that of control. N o differences were noted among treated groups. The results suggest that the effect of combined cold (5°C) and hypoxia (14% oxygen) on water exchange is not a summation of that occurring separately during cold and hypoxia, as judged by the relationship between water intake and the urine output, by the extent of post-environmental drinking, and by serum osmolality.Abstract
It is well known that experienced pilots suppress their labyrinthine stimuli. We wanted to know if the sensitivity to linear motion could be habituated by repeated, strong vestibular stimuli. Fifteen subjects without experience of flight and 18 experienced military pilots were used for the experiments. They were rotated in a modified Stille-Werner CF 10 rotating chair with head and body 1 m from the rotating centre. Two positions were used: heading forwards and heading centripetally. The task of the subjects was to estimate the apparent change in space of a luminous cross movable in the three axes of the space. In the first position, both groups underestimated the inclination of the resultant vector. In the other position, the pilots underestimated the inclination and the nonpilots overestimated it, but the difference is not statistically significant. No conclusions are possible here. If the results of the pilots are plotted against their amount of flight hours, there is a clear correlation between the flight training and the capacity to give a correct response. The cause of these results is discussed.Abstract
The Skylab II mission was launched at 1300 GMT on 25 May 1973 and returned to earth on 22 June 1973 at 1350 GMT. The command module was equipped with passive dosimeters located at five selected stations within the spacecraft to monitor radiation levels accumulated during the space mission. The passive sensors were prepared jointly by the Air Force Weapons Laboratory and the Air Force Academy as part of a larger series of radiation measurements conducted by the Department of Defense on the Skylab program. The passivesensors consisted of an array of thermoluminescent devices, ionization chambers, and activation foils. The thermoinminescent unitschosen were the EG&G double-chip type encased in evacuated glass containers. Both lithium fluoride and manganese activated calcium fluoride were seIeeted for use in the Skylab missions. The ionization chambers employed in these measurements were the Dosimeter Corporation tissue equivalent quartz fiber discharge chambers. The measurements presented in this report include no influence of solar flare particles, since no major solar flare particle events were observed in the Skylab I-II mission. Solar particIes in the Skylab orbit would be largely shielded by the earth’s magnetic field, except for short time exposures at the highest latitudes. This shielding should be sufficient to prevent any hazardous radiation levels from reaching the astronauts, even from very large particle events. Polar orbiting manned satellites would, of course, be subject to high fluences of solar particles. Manned missions operating at higher altitudes, even in equatorial orbits >300 nm, for extended periods would accumulate significant exposures which wouId limit crew time on orbit. Practicable shielding appears to reduce the exposure levels only by a few per cent due to the high energy of the trapped proton component of the space radiation environment.Abstract
Bacillus thuringiensis vat. thuringiensis spores flown in the Apollo 16 Microbial Response to Space Environment Experiment were examined for viability and alterations in toxin production capability. Exposure of the spores to full sunlight in space resulted in a significant reduction in viability which is in accord with ground-based studies. Exposure of the spores to space conditions without light or to space conditions in conjunction with solar ultraviolet irradiation at peak wavelengths of 254 and 280 nm did not alter survival rates. Statistically significant differences in the capability of the postflight isolates to produce toxins were not found between any of the treatment groups including the ground-based controls.Abstract
Ten purebred Beagle dogs (all males) were used to determine the effect of a prolonged stay in a locked environment (i.e. no exogenous microbial contamination) on the microbial flora. Seven dogs were put into four sterile, germ-free dog isolators, fed a steam-sterilized diet and water, and supplied with sterile air. Three control dogs were housed in conventional dog holding facilities but were fed the same steam-sterilized diet used for the isolated dogs. At monthly intervals the microbial profile (feces, nose, and throat) of each dog was assessed. After 12 months the following results were observed: a. There has been no drastic alteration or simplification of the microbial profile of isolated or control dogs; b. Although isolated dogs had slightly higher levels of anaerobic bacteria and somewhat lower levels of enterococci, the major groups of anaerobic, aerobic, and facultative bacteria remained qualitatively and quantitatively similar for the 12- month study period; and c. although they were only minor components of the fecal flora, Candida albicans and Shigella sonnei were consistently isolated in larger numbers from the dogs in the locked environment.Abstract
Five male subjects were monitored for energy cost and recovery profiles after mild (433 ± 13 kg.m/min) work in air and immersed at water temperatures of 26° and 20°C. Recovery measurements included heart rates, rectal temperatures, and oxygen consumptions. Heart rates were not different during work under all conditions, but post-exercise recovery to resting rate was faster after exposure to 20°C water. Rectal temperatures dropped faster during working immersions than during immersions without work, and continued to fall during recovery, with the greatest rate of fall following 20°C water exposure. Oxygen uptakes were greater in water than air, the highest cost being in 20°C water, although the oxygen cost of the work per se was not different. The results suggest that thermal recovery is retarded after work in colder water and the energy cost may constitute a significant percentage of daily caloric intake even for mild exposures.Abstract
Squirrel monkeys were trained to avoid increases in artificial gravity on a 15.2-m (50-ft) diameter centrifuge with programmable radius and angular velocity. Subjects were restrained inside a centrifuge capsule where depression of a lever switch reduced artificial gravity or postponed programmed increases. Performance of subjects trained to avoid increased gravity produced by increasing angular velocity was compared with performance to avoid increases produced by increasing rotation radius. In the range 1.05-2.05 G, similar patterns of avoidance responding were generated whether changes in artificial gravity were produced by varying rotation rate or radius. Transfer of animals trained with variable angular velocity to variable radius and vice versa had no effect on gravity avoidance behavior. These results support previous findings indicating that combinations of angular velocity and radius which produce the same artificial gravity have similar behavioral effects.Abstract
Vestibular side effects including visual and postural illusions, nystagmns, and motion sickness were elicited using a vibrator (held either by the subject or experimenter) applied to different regions of the head. Although a commerclally available vibrator (60 Hz, 120 pulses/s) can elicit side effects, its use was enhanced by varying the vibration frequency and optimizing the stimulus conditions. Both horizontal and vertical nystagmus were elicited, the latter inconsistently. A strong apparent movement (and displacement) of a dimly lighted target that resembled the oculogyral illusion and apparent self-motion were consistently elicited. Motion sickness was readily evoked in some subjects; other subjects were immune, although the periods of stimulation were brief. The findings indicate that the use of a vibration stimulus should be exploited from the theoretical and practical viewpoints.Abstract
We have demonstrated previously that lysis of lilies by hyperoxia was preceeded by peroxidafion of RBC lipid. The present studies were undertaken to identify a population of RBCs, by age, which was more susceptible to this effect. Tocopheroldeficient and chow-fed mice were injected with 59Fe citrate. Seven days later the same mice were injected with 55Fe citrate. Three days after this injection, mice were exposed to hyperoxia (OHP). After OHP, serial determinations of Hct, appearance of plasma, and specific activities of the isotopes in cells and plasma were made. No significant changes were observed in chow-fed mice. Immediately after OHP, tocopherol-deficient mice had normal Hcts. As hemolysis evolved, a five-fold increase of 59Fe activity ("early" label) in plasma was observed with concomitantly decreased activity in remaining RBCs. No significant change of 55Fe activity was noted in plasma or RBCs. These data indicated that older RBCs were more susceptible to lysis by hyperoxia.Abstract
A 52-year-old asymptomatic man was evaluated with left heart catheterization and coronary angiography because of an abnormal response to exercise testing. His functional and aerobic capacity were exceptional. The left ventricular angiogram and LVEDP were completely normal in spite of total occlusion of the RCA and LCx and 90% narrowing of the proximal LAD. Kugel’s artery was demonstrated by cineangiography as an important source of collateral flow from the proximal to distal RCA.Abstract
A discussion of the objectives of the Air Force Aerospace Medicine Residency Program is presented. This discussion serves to delineate many of the unique aspects of the specialty of aerospace medicine and also emphasizes those qualifications possessed only by the specialist in this field of medicine. The nature of present and future challenges in the specialty is also considered.Abstract
Aircraft accident survivors who later develop retrograde amnesia for the circumstances of their crashes present unique problems in terms of psychiatric treatment and valid accident investigation. The authors explore the complexities of treating such patients within the limitations of our present understanding of amnesic disorders and raise questions concerning medicolegal issues of informed consent, confidentiality, and validity of information recalled during the treatment process.Abstract
Motion sickness under experimental conditions cannot only be evoked through summation of vestibular Coriolis effects elicited during actual body rotation but also through optokinetic pseudo Coriolis effects evoked by head movements during an illusory body rotation. Hence, it is worthwhile to investigate the comparative effectiveness of some anti-motion-sickness drugs. The antihistamine, dimenhydrinate, and the belladonna-alkaloid, scopolamine, both reduce nausea and apparent tilt (separately scaled) after each head movement performed during pure vestibular, pure optokinetic and vestibular stimulation. The drugs diminish the occurrence of severe motion sickness as indicated by rating of symptoms and the number of subjects vomiting. Magnitude estimations of nausea and apparent tilt were found to be more reliable for evaluation of drug effectiveness than ratings. Vestibular nystagmns thresholds and subjective acceleration thresholds increase after drug administration, postrotational nystagmus is suppressed, and angular velocities of optokinetic saccades are lowered. Central sedative effects, about which subjects complained, were documented by psychological efficiency tests. On the basis of the results, one may hypothezise that the vestibular nuclei are a relay station also for provocation of optokinetics motion sickness and one of the possible sites of the pharmacological action in preventing optovestibular motion sickness.Abstract
The author has prepared this paper with two aims—a) to transmit the image of the high-risk physician in the middle of his journey through time and space, with the hope it may have some prophylactic value in re-educating both the doctors and those who care for them to early danger signals of distress; and b) to provide the background for future research on “Decision Making and Human Factors,” as a most tentative effort to tease out significant variables in the 80 to 90% of aircraft accidents attributable to “pilot error.”Abstract
The control of malaria can be accomplished by eHmlnating the Anopheline mosquito vectors or by reducing the incidence of malaria in the human population with suppressive antimalarial therapy. A combination of both antimosquito measures and suppressive chemotherapy has been the basis for a program of world-wide eradication of malaria. During the month of December, 1971, 12 new cases of malaria were diagnosed. All individuals denied taking the antimalaria tablet. The basis of this study was to determine the possible etiology of the increased incidents of malaria which occurred among personnel at Phan Rang AB, RVN.Abstract
This blood pressure measurement device was designed to meet an urgent operational requirement for a method of monitoring vital signs of acutely ill patients while in flight. The high noise and vibration levels of most aircraft make indirect measurement of blood pressure extremely difficult using the conventional approach. A method using ultrasonic monitoring that employs the Doppler shift principle to detect blood flow and arterial wall motion was developed by the USAF School of Aerospace Medicine. The in-flight blood pressure measurement device consists of a commercial ultrasonic Doppler shift monitor and a standard sphygmomanometer which has been modified by placing a transducer mount through the cuff and bladder. Its use is very similar to that of an acoustic stethoscope and sphygmomanometer; however, systolic and diastolic values are determined by monitoring arterial wall motion rather than detecting Korotkoff sounds. This device has proven to be extremely effective in eliminating the effects of in-flight noise and vibration, and is sufficiently sensitive to determine blood pressure of patients in shock.Abstract